Common turbo failures such as overspeeding can cause severe fatigue to the shaft and wheel. Signs of fatigue include partial loss of blades caused by the constant flexing of blades beyond the designed parameters. Fatigue is a mode of failure not the cause.
Traditionally, a shaft and wheel has an open back with a slender or straight shaft. To strengthen the turbine wheel, Melett introduced design improvements and developed a full back shaft and wheel solution, which reduced the risk of fatigue on the inducer diameter.